The present invention relates to an information processing device and method, and a recording medium, and particularly to an information processing device and method which are suitably used for a device for decrypting encrypted data, and a recording medium.
For example, in satellite broadcasts for distributing programs through a satellite, the program data are encrypted and then distributed to audiences so that a person who has no contract (i.e., a non-contractor) is prevented from watching/listening to the program. Accordingly, when the receiver of a person who has made a contract (i.e., a contractor) receives encrypted data, the encryption of the data thus received is canceled, and the contractor can watch/listen to the programs. On the other hand, when the receiver of a non-contractor receives encrypted data, the data are not decrypted and thus the non-contractor cannot watch/listen to the programs.
A key for decrypting the encrypted data (i.e., a key for authentication) is stored in the receiver for receiving the encrypted data as described above, and the encryption of the data is canceled (i.e., the encrypted data are decoded by using the key). The key is renewed every predetermined period so that a non-contractor is prevented from unjustly using the information of the key itself.
Communications of encrypted data (i.e., encrypted communications) are also carried out in a digital interface, such as an IEEE1394 interface. In the case of such encrypted communications, devices that mutually make communications with each other execute authentication processing, and if it is judged that the reception/delivery of the contents is permitted therebetween, the content-receiving side can decode (decrypt) the encrypted data (i.e., cancel the encryption) by jointly owning a key for canceling the encryption. In this encrypted communication, the key is renewed every predetermined period.
When the renewal processing of the key fails, the encrypted data cannot be decoded in some cases. Further, the decoding may fail due to other causes. When the decoding fails, backup may be carried out for decoding-failed data. Even when backup is not indispensable, noises may occur.